A Cloud of Uncertainty Hangs Over Mexican Elections : Politics: Following the slaying of Luis Donaldo Colosio, Congress quietly passes reform package. Critics say the changes are not enough to guarantee clean voting.

JUANITA DARLING and TRACY WILKINSONTIMES STAFF WRITERS

Mexicans began the traditional Easter week vacation Saturday under a cloud of uncertainty caused by the murder of Luis Donaldo Colosio and apprehension about its effects on Aug. 21 federal elections.

Concerns about whether the elections will be free of fraud and how voters will react if they are not have been fueled by Wednesday's assassination of Colosio, presidential candidate of the ruling party.

While the rest of the nation mourned Colosio last week, the Mexican Congress quietly passed a long-anticipated electoral reform package aimed at ensuring that those elections will be fair.

The reforms were originally considered a response to demands for democracy raised by rebels who briefly took several towns in the southern state of Chiapas on Jan. 1.

But they have taken on an added significance in the wake of Colosio's death and the questions it has raised about the Mexican political system, which is dominated by the Institutional Revolutionary Party (PRI) that has stayed in power for six decades through a combination of patronage, co-optation and vote fraud.

The changes were the most extensive of the three reform packages enacted during President Carlos Salinas de Gortari's administration. But they are not enough to guarantee the clean elections needed to democratize the country, some critics have said.

In another development Saturday, some of Mexico's most prominent political figures paraded through Salinas' office in the presidential residence in a condensed version of the traditional consultations that precede the nomination of the ruling party's candidate for president.

None of those who spoke with Salinas would comment on their conversations.

Because the PRI has not lost a presidential election in its 65-year history, the party's nominee automatically becomes the front-runner, making the selection a matter of intense national interest.

Callers to a radio talk show made pitches for their favorite potential candidates, while some party activists publicly declared support for PRI Chairman Fernando Ortiz Arana--even as party leaders insisted on silence about the subject.

PRI leaders issued a statement from Ortiz Arana "disauthorizing any expression of support in favor of any person whatsoever until the party . . . sets the terms for its internal process."

Also Saturday, the Defense Ministry denied accusations made by the southern rebels that the Mexican army has bombed areas in guerrilla-held territory or is planning a new attack. The ministry reiterated its support for efforts to find a peaceful solution to the conflict in Chiapas.

Government peace envoy Manuel Camacho Solis said he has passed that message on to the rebels, who call themselves the Zapatista National Liberation Army.

The Zapatistas said in a communique Friday that they have broken off their consultations with grass-roots supporters on last month's government peace proposal because they believe the army plans to attack them.

The continuing problems in Chiapas and disquiet over the selection of the new PRI candidate cast a cloud over the traditional Easter week holiday spirit.

Legislators had hoped that the special congressional session called to approve electoral reforms would have provided reassurance that the country was moving toward a democratic opening.

Senate majority leader Carlos Jimenez Macias said the reforms, approved late Thursday, had promised to foster "a climate of respect, tolerance, dialogue and the adoption of agreements that guarantee the widest civil liberties and solid social stability in the Aug. 21 elections." But he added that "the deplorable exercise of violence that cut short the life of Luis Donaldo Colosio resurrects a grave risk of political backsliding."

The reforms give citizens not affiliated with political parties the majority of votes on the 11-person Federal Electoral Commission, the agency that will run the election.

They also provide for a limited audit of voter registration lists and a special prosecutor to enforce stricter penalties for election fraud.

The reforms submitted to the Mexican Congress were reached in negotiations among the Interior Ministry and the three major parties: the PRI; National Action Party, known as PAN, and Democratic Revolutionary Party, known as the PRD.

Nevertheless, PRD presidential candidate Cuauhtemoc Cardenas, who many Mexicans believe lost the 1988 presidential race because of fraud, said the reforms do not go far enough.

"I support measures that will guarantee clean elections," he said, "but I cannot recognize as such measures that pretend to assure clean elections on Aug. 21 when they are nothing more than limited changes that do not correct at their roots the rigidity and partiality of electoral structures and mechanisms."

Cardenas presented a seven-point objection to the reforms, including concerns that the interior minister will still be on the electoral commission--limiting its independence from the government.